1. Field of the Invention
This invention relates to a method of construction, as well as, apparatus for a furnace crown or the like. More specifically this invention deals with the means and method of maintaining the support and integrity of said crown, and a means and method by which the problems associated with maintaining the integrity of the crown can be overcome. The invention taught herein is suitable as a crown for use with furnaces operated at high temperatures. The teachings of the present invention also apply to suspension systems for ceilings in commercial, industrial and residential construction circumstances.
Known in the art are many methods of constructing furnace crowns, the most common method being the traditional vault type which has in its commonest form a semicircular or arch section resting on two sidewalls. This description is familiar to those skilled in the art and has been a preferred method of kiln construction since the earliest recorded history of kiln construction. However, constructing a furnace crown using this method (and constructing the necessary side walls to support said crown) involves considerable construction costs both with respect to materials utilized and complexity of construction.
The crown of a kiln of this prior art must have considerable thickness in order to be effective as an insulator. In order to support this mass the sidewalls must be large. The enormous mass of the structure requires large amounts of energy in order to reach a temperature high enough for modern ceramic firing. The mass of the structure, and the excessive retention of heat, results in extended cool down time which inhibits maintenance of the crown and replacement of ceramic materials to be fired.
Other problems with this prior art and its derivatives, are that refractory materials used in the construction of these furnaces tend to deteriorate and cause faults with the material being fired by contact. This prior art method of construction leaves little or no possibility of economical reconstruction and rehabilitation of the furnace.
2. Description of the Related Art
Besides the numerous variety of forms generally derived from the construction method described above, there exist a number of suggested ways to suspend refractory brick, and systems developed to suspend whole furnace crowns. Most relevant to the present invention would be "Supporting Structures for Furnace Crowns" U.S. Pat. No. 4,539,919 9/1985, Bossetti, which depicts inverted "T" beams and anticipates their ability to suspend insulating material. However, the invention referred to therein has no other supporting mechanism other than reliance upon the strength of the sidewalls of the supporting structure. The present invention disclosed herein provides for a system of supports which greatly enhance the weight bearing capacity, longevity, and ease of maintenance of the furnace crown.
Furthermore, there are quite a number of methods for suspending refractory brick from structures which do not contribute to the insulating qualities of the furnace crown. An example of such a supporting structure is the "Thermally Insulated Enclosure" U.S. Pat. No. 4,083,155 4/1978 Lampert. A defect in the Lampert method of constructing furnaces is the interdependence of the various suspended blocks of insulating material, which makes for costly maintenance in the event of a failure of one section.
Other such structures suspend insulating material other than refractory brick, such as "Kilns" U.S. Pat. No. 4,081,236 3/1978, Corbett. However, this system fails to address the problem of section failure and subsequent maintenance of the structure.
Finally, refractory brick has been patented with support means constructed into the brick, such as "Ceiling and Wall Construction" U.S. Pat. No. 4,628,657 12/1986, Ermer. However, this system also relies on the structural interdependence of each brick, using "bearing bricks" to act as insulators and support structures without the possibility of replacing individual sections of the crown or sections of the support mechanism without resorting to the destruction of the viability of the entire structure.
Still another means and method used in industry consists of using an inverted T-rail comprised of a suitable ceramic material attached to a ceramic bone which is further attached to a hanger device. A number of these T-rail/bone/hanger assemblies are suspended from a support system forming adjacent rows. Layers of insulation, a combination of board and blankets, of a determined size and temperature resistance are supported by and evenly separate these inverted T-rail rows.
Numerous problems are associated with this system. The individual T-rails which comprise the rows have a constant width attachable end, thus when removing or replacing any of these ceramic attachment bones it must be done by sliding it off the end of the individual T-rail (i.e. at a T-rail junction). This is quite inconvenient because it requires disruption of the T-rail row as well as the insulation layer. The portion of these T-rails supporting the insulation does not cover an adequate surface area of the insulation thus resulting in eventual sagging of this insulation. The bones, as referred to above, are slid into place and are not held into position by the bulk wool which is placed between them, thus the bones move during kiln vibration causing considerable stress upon these bones, eventually leading to breakage. In this system the insulation layers completely encompass the attachment bone as well as the curved lower portion of the hanger. Because of this exposure to considerable heat, as well as the drastic change in temperature (insulated to external air) these hangers fail over time. The bulk wool used to fill in the area found above the T-rails and the between the insulation rows is thermally inefficient and is difficult to remove when replacing the bones and/or T-rails. The bone'5 attachment hole through which the hanger is hooked is shaped as a straight cylinder providing only two points of contact (i.e. stress) between the bone and hanger, again leading to considerable breakage of these "bones". (See FIG. 13 for prior art)
3. Objectives of the Invention
Accordingly it is an object of this invention to teach a new and improved method and means for a kiln crown system.
Another objective is to create a furnace crown which can easily be maintained with replaceable support structures and insulating material such that said supporting mechanisms and insulating materials may be replaced without the need for dismantling the entire crown or causing the remaining sections of the crown to become unstable.
Still another object of this invention is to create a system of crown construction such that the structural integrity of the whole system and its component parts is enhanced.
Still another object of this invention is to allow the crown to withstand and efficiently insulate temperatures in excess of 3000.degree. F. while protecting the supporting components from thermal shock.
Still another objective is to provide for a efficient method of construction for a kiln crown system.
Still another objective of the invention is to provide for a new and improved T-rail such that the design of the T-rail provides for easy installation as well as removal during repair of a kiln crown.
Still another objective is to provide for a new and improved T-rail with a slot and stop system which allows the T-rail to be easily attached to a suspension means.
One final objective is to provide for a kiln crown system, as well as a method for accomplishing a kiln crown system, which has an easily adjustable height.
These and still further objectives will become apparent hereinafter.